247 



Leioptekia rafinesquii. Hall. (Fig. 162.) (Pal. X. V.. 

 Vol. V., Pt. I., p. 161, Pis. XV.. XX., 

 LXXXVI1I.) 



Distinguishing Characters. — Oblique, 

 narrowly ovate body, with height equal 

 to or greater than the length ; flat 

 wing, with concave margin and acute 

 extremity ; short, obtuse, convex ear. 



Found in the Demissa bed (very 

 rare). 



Fig. 162. Leiopteria rafin- 

 esquii. A left valve (from 

 Hall). 



Leioptekia conradi. Hall. (Fig. 162A.) (Pal. X. Y., 

 Vol. V., Pt. I., p. 159, Pis. XX, LXXXVIII.) 



Distinguishing Characters. — Strong obliquity; hinge line 

 longer than length of valve, greatly extended posteriorly ; 



Fig. 162A. Leiopteria conradi. Two left valves and a right valve, of different sizes, 

 showing variations (from Hall). 



acute extremity, and concave posterior margin of wing; 

 small ear separated from shell by rounded sulcus; irregular, 

 often crowded, concentric stria?. Readily distinguished from 

 the species of Actinopteria occurring with it, by the absence 

 of rays. 



Found in the Hamilton group, at West Hamburg, Erie 

 Co, X. Y. (Coll. Am. Mus. Nat, Hist. Xew York.) 



